Thermogravimetric analysis as a useful tool for adsorbed water assessment: case of bentonite

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4. Thermogravimetric analysis as a useful tool for adsorbed water assessment: case of bentonite

The chemical structure of clays is a significant determinant of their behavior, particularly in the case of active clays renowned for their high-swelling and hydro-isolating characteristics. These properties make them valuable in diverse geotechnical applications, including nuclear waste repositories and landfills. High swelling capacity and low permeability originate from the water physically attracted to clay particles, often termed "adsorbed" or "physisorbed" water. This water exhibits distinct features such as an ordered structure, higher density, and unique dielectric constant compared to bulk liquid water. Its interaction is influenced by factors like pore water salinity, degree of saturation, and temperature of the waste at repository. Predicting the mechanical response, such as swelling upon hydration, necessitates advanced modelling considering the physical-chemical interplay between water and clay particles. Accurate multi-physical predictions rely on precise microstructural investigations, crucial for understanding active clay behavior. This study introduces a novel methodology utilizing Thermogravimetric Analysis (TGA) to quantitatively assess adsorbed water in active clays. Employing this approach provides fresh insights into the types and quantities of water retained at different saturation levels of MX-80 bentonite. These findings can be incorporated into mechanical prediction models to augment their precision.

28th European Young Geotechnical Engineers Conference (EYGEC2024)

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